1. Field of the Invention
The present invention concerns a tightening device with a swiveling arm. It also deals with the equipment provided with this tightening device, for example portable tools, and in particular portable chain saws.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
It is common to use a screw or a nut screwed on a threaded rod to obtain a tight grip between two parts. A part mounted by means of a screw-nut system presents the advantage of being removable. However, its disassembly and subsequent reassembly require the loosening of the nuts or the screws by means of an independent tool such as a wrench or a screwdriver, and then their re-tightening by this same tool. Now, one does not always have such a tool available, which may be lacking at the very moment when one needs to loosen and/or tighten nuts or screws.
Also, it happens frequently that a screwdriver or a wrench may slip off inadvertently from the head of the screw or from the nut during the operation. Therefore, the tightening and loosening of a nut or a screw make it sometimes necessary to know how to combine force and skill.
Portable chain saws are generally equipped with a screw-nut device to perform the tightening and blocking, in the desirable position, of the guide bar, to allow a tension adjustment of the chain or the installation of a new chain.
In such an application, one can see that the operator must always have within reach a specific tool for loosening or tightening the nut or the set screw, especially during use of the tool out of doors when one may have to perform tension adjustments of the chain saw.
To mitigate this constraint, one has proposed (DE-29909645 U1) a tightening device for the guide bar of a chain saw, by means of a screw-nut system according to which the nut of the system is permanently secured to a handling wrench which can be folded back against the tool housing, in a neutral position when not in use. According to this device, a rotary ring is placed under the head of the nut and the wrench is fastened with a capability of swiveling on this ring, around an axis that is perpendicular to the axis of the nut and in an offset manner in relation to the latter. On the other hand, two radial grooves have been made on the head of the nut, while the wrench is provided with a tooth which, depending on the swiveled position of said wrench, can mesh with one of said grooves to allow the rotary actuation of the nut in one direction or the other, or be disengaged from said grooves to let the wrench rotate freely around the nut.
This device requires, prior to the rotary movement of the nut or the placement of the wrench in the storage position, an obligatory engaging or disengaging operation, whatever the case may be, or an operation which may not be immediately understood by the users.
The aim of the invention is at least to propose a solution to the problems deriving from the various constraints exposed above.